Audio Systems: XM Radio presets not holding, memory battery, pioneer deh

Question
Hi,
  This is probably a stupid question,but I can't figure it out. I have a Pioneer DEH-P2500 head unit,and a Pioneer GEX-P910XM Satellite receiver. When I preset XM channels,they stay preset until I shut off the car-when I restart the car,the XM is back on Channel 1 and all the presets are erased. I thought it might be a wiring issue,but the clock is still correct,and the am/fm presets are still set. If it was wired wrong,shouldn't all the presets clear when the car is shut off? As long as the motor's running,the XM presets hold,but when it's shut off,even for a second,they're gone. If there is enough current to keep the clock and am/fm presets,why would it lose the XM ones? Maybe something with the receiver itself,and not the head unit? I'm lost,so any help you can give me will be greatly appreciated.
Thank you!
Greg

Answer
Hello Greg,
It's possible that the XM unit has a memory battery inside that needs replacing. These XM units are designed to be moved from one vehicle to another and the program memory should hold during moving.
TOM,
T&D ELECTRONICS
tdeser@zoominternet.net